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DIETS are associated with lifestyle conditions
like obesity, diabetes and heart disease. It is often not appreciated that what
is eaten has implications not only for physical health, but also mental health.
The brain is the master of the body as it
controls almost all bodily function, even when one is asleep. It is very
complex, and is believed to be the final frontier of science.
The brain requires nutrients just like the
heart, lungs or muscles do. Some foods may increase the risk of neurological
and psychiatric conditions like depression and dementia, whereas other food may
be protective.
But which foods are important to keep our grey
matter happy?
Knowledge about this is still in its early
days, but there are research findings that can increase the chances of
maintaining a healthy brain well into the senior citizen years.
Wholegrains
The brain requires energy for its functions. As
this is dependent on the body’s blood flow, it goes without saying that
cardiovascular health is crucial for mental health.
An adequate and steady supply of glucose in the
bloodstream enhances concentration and focus.
This is achievable with the consumption of
wholegrains with a low glycaemic index, ie those that release glucose slowly
into the bloodstream, thereby keeping energy levels stable and enabling a
person to be mentally alert throughout the day.
Wholegrains with low glycaemic indexes include
granary or seeded bread, brown rice or pasta, oatmeal and sweet potatoes.
Oily fish
The body cannot produce essential fatty acids
(EFA); therefore, they have to be obtained from food.
The omega-3 fatty acids are essential for health
and normal brain function, growth and development.
Research findings have demonstrated that
omega-3 fatty acids reduce inflammation and may lower blood pressure, which
affects brain health.
They have also been shown to reduce cholesterol
and triglyceride levels, the formation of plaques on arterial walls, blood
pressure, and abnormal heart rhythms – all of which reduces the likelihood of
cardiovascular disease.
The most effective omega-3 fatty acids
(polyunsaturated fatty acids) are eicosapentaenoic acid (EPA) and
docosahexaenoic acid (DHA). Both EPA and DHA are needed for functioning of the
brain, heart and joints.
DHA plays an instrumental role in the
development of the nervous and visual systems of newborn children.
Oily cold-water fish like mackerel
contain the necessary EPA and DHA needed for the functioning of our brain,
heart and joints.
It is also important for brain function in
adults. Low DHA has been found to be associated with an increased likelihood of
developing memory loss and Alzheimer’s disease.
It has been reported that there is a
correlation between fish consumption and lower likelihood of psychotic symptoms.
There is also a suggestion that fish oil may prevent psychosis in individuals
at increased risk.
EPA and DHA have both been shown to be of
benefit in depression and postpartum depression respectively. Conversely, there
is a suggestion that omega-3 deficiency may increase the risk of suicide.
The American Heart Association recommends
eating fish, especially fatty fish, at least two times (two servings) a week.
Oily cold-water fish like salmon, mackerel,
trout, tuna, herring and sardines contain ready-made EPA and DHA for the body
to use. Other sources of omega-3 fatty acids include linseed (flaxseed) oil,
soya bean oil, pumpkin seeds, walnut oil and soya beans.
Berries
Berries contain anthocyanins, which have
anti-oxidant and anti-inflammatory properties.
The consumption of blueberries may be effective
in delaying or improving short-term memory loss.
Animal studies have demonstrated that a diet of
strawberry, blueberry or blackberry extracts lead to a reversal of age-related
deficits involving learning and memory.
Other studies have reported that blueberries
reduced the effects of Alzheimer’s disease or dementia, and improved the
learning capacity and motor skills of aging animals.
In addition, it was reported recently in Circulation, a journal of the
American Heart Association, that the risk of a heart attack may be reduced by
as much as one-third in women who ate three or more servings of blueberries and
strawberries per week.
Tomatoes
Tomatoes contain an antioxidant called
lycopene. It is also a source of niacin, which has been used for years to
increase HDL (good cholesterol) and lower LDL (bad cholesterol).
There is evidence that consumption of tomatoes
could provide protection against free radical damage to cells that occur in the
development of dementia, especially Alzheimer’s disease.
Vitamins
Raised levels of homocysteine have been
associated with an increased risk of stroke, cognitive impairment and
Alzheimer’s disease.
A trial in Oxford, England, reported that “the
accelerated rate of brain atrophy in elderly with mild cognitive impairment can
be slowed by treatment with homocysteine-lowering B vitamins”. These vitamins
were B6, B12 and folic acid.
They concluded that “since accelerated brain
atrophy is a characteristic of subjects with mild cognitive impairment who
convert to Alzheimer’s disease, trials are needed to see if the same treatment
will delay the development of Alzheimer’s disease”.
The B vitamins are found in high-protein foods
like fish, meat, poultry, eggs and dairy, as well as some leafy, green
vegetables, beans and peas.
Among the benefits attributed to vitamin C is
an increase in mental agility. The sources of vitamin C include leafy green
vegetables, cabbage, broccoli, cauliflower, papayas and citrus fruits.
Broccoli is also a source of vitamin K, which
is believed to enhance cognitive function.
A report in the American Journal of Epidemiology suggested that an intake of vitamin E
may prevent cognitive decline, especially in senior citizens.
It concluded that “decreasing serum levels of
vitamin E per unit of cholesterol were consistently associated with increasing
levels of poor memory after adjustment for age, education, income, vascular
risk factors, and other trace elements and minerals. Serum levels of vitamins A
and C, beta-carotene and selenium, were not associated with poor memory
performance in this study”.
The sources of vitamin E are nuts, leafy green
vegetables, asparagus, olives, seeds, eggs, brown rice and wholegrains.
Zinc
Zinc plays an important role in modulating spatial
learning and memory.
But it has to be remembered that dietary
fortification and supplementation of zinc could lead to overdose, with
consequent toxic effects on brain function.
Animal studies have shown that high dose
supplementation of zinc induces specific zinc deficiency in the hippocampus of
the brain, leading to impairment of learning and memory.
As such, it is important to keep to the
recommended daily allowance (RDA), which varies with age, pregnancy and
lactation.
Red meat and poultry are common sources of
zinc. Other sources include beans, nuts, seafood like oysters, crabs and
lobsters, wholegrains, fortified breakfast cereals, and dairy products.
Supplements
The relationship between diet and dementia has
still to be fully elucidated. However, there are important links that are worth
acting on.
A well-balanced diet provides the brain the
best opportunity of avoiding disease. If the diet is not balanced for whatever
reason, supplements of omega-3 fatty acid, multivitamins and minerals may be
useful.
It is advisable to discuss this with the doctor
prior to commencing supplements, as excess amounts will lead to adverse
effects.
Mediterranean diet
The benefits of a Mediterranean diet have been
publicised often. Although there are several countries bordering the
Mediterranean, the term commonly refers to the diets of Italy, Spain and
Greece.
This diet includes a proportionally high
consumption of fruits, vegetables, nuts, wholegrains, fish and unsaturated fats
(common in olive and other plant oils); moderate consumption of dairy
products like yoghurt and cheese; and low consumption of meat and meat
products.
Studies have reported that those on a
Mediterranean diet are up to 30% less likely to develop depression, compared to
those taking more meat and dairy products.
Consumers of more olive oil have a lower risk
of ischaemic stroke, mild cognitive impairment and Alzheimer’s disease,
especially when they are physically active.
(Dr
Milton Lum is a member of the board of Medical Defence Malaysia.)
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